Method for determining an over-pressure in a fuel storage means of an injection system of an internal combustion engine

Abstract

A method for determining an overpressure in a fuel reservoir of an injection system of an internal combustion engine, in particular in a common rail of a common rail system, the pressure in the fuel reservoir being sensed, an overpressure in the fuel reservoir being identified if the derivative of the sensed pressure over time exceeds a predetermined slope threshold value and the sensed pressure then exceeds a predetermined pressure threshold value.

1 - 10 . (canceled) 
     
     
         11 . A method for determining an overpressure in a fuel reservoir of a common rail injection system of an internal combustion engine, the method comprising:
 sensing the pressure in the fuel reservoir; and   identifying an overpressure in the fuel reservoir if the derivative of the sensed pressure over time exceeds a predetermined slope threshold value and the sensed pressure then exceeds a predetermined pressure threshold value.   
     
     
         12 . The method of  claim 11 , wherein an overpressure in the fuel reservoir is identified only if the sensed pressure exceeds the predetermined pressure threshold value within a predetermined first time span after the derivative of the sensed pressure over the time last exceeded the predetermined slope threshold value. 
     
     
         13 . The method of  claim 11 , wherein an overpressure in the fuel reservoir is identified only if the sensed pressure exceeds the predetermined pressure threshold value for longer than a predetermined second time span. 
     
     
         14 . The method of  claim 11 , wherein an overpressure in the fuel reservoir is identified only if the derivative of the sensed pressure over time exceeds the predetermined slope threshold value for longer than a predetermined third time span. 
     
     
         15 . The method of  claim 11 , wherein at least one of a fuel pump, which makes fuel available to a metering unit, and a high-pressure pump, which pumps fuel into the fuel reservoir, is shut off when an overpressure is identified. 
     
     
         16 . The method of  claim 11 , wherein fuel is discharged out of the fuel reservoir when an overpressure is identified. 
     
     
         17 . The method of  claim 11 , wherein a fault count value is provided that is incremented when an overpressure is identified. 
     
     
         18 . A control unit for determining an overpressure in a fuel reservoir of a common rail injection system of an internal combustion engine, comprising:
 a sensing arrangement to sense the pressure in the fuel reservoir; and   an identifying arrangement to identify an overpressure in the fuel reservoir if the derivative of the sensed pressure over time exceeds a predetermined slope threshold value and the sensed pressure then exceeds a predetermined pressure threshold value.   
     
     
         19 . A computer readable medium having a computer program, which is executable by a processor, comprising:
 a program code arrangement having program code for determining an overpressure in a fuel reservoir of a common rail injection system of an internal combustion engine, by performing the following:
 sensing the pressure in the fuel reservoir; and 
 identifying an overpressure in the fuel reservoir if the derivative of the sensed pressure over time exceeds a predetermined slope threshold value and the sensed pressure then exceeds a predetermined pressure threshold value. 
   
     
     
         20 . The computer readable medium of  claim 19 , wherein an overpressure in the fuel reservoir is identified only if the sensed pressure exceeds the predetermined pressure threshold value within a predetermined first time span after the derivative of the sensed pressure over the time last exceeded the predetermined slope threshold value. 
     
     
         21 . The computer readable medium of  claim 19 , wherein an overpressure in the fuel reservoir is identified only if the sensed pressure exceeds the predetermined pressure threshold value for longer than a predetermined second time span. 
     
     
         22 . The computer readable medium of  claim 19 , wherein an overpressure in the fuel reservoir is identified only if the derivative of the sensed pressure over time exceeds the predetermined slope threshold value for longer than a predetermined third time span. 
     
     
         23 . The computer readable medium of  claim 19 , wherein at least one of a fuel pump, which makes fuel available to a metering unit, and a high-pressure pump, which pumps fuel into the fuel reservoir, is shut off when an overpressure is identified. 
     
     
         24 . The computer readable medium of  claim 19 , wherein fuel is discharged out of the fuel reservoir when an overpressure is identified. 
     
     
         25 . The computer readable medium of  claim 19 , wherein a fault count value is provided that is incremented when an overpressure is identified.